April 28, 2008
Physicist sheds light on Da Vinci
BY carol clark
A centuries-old mystery about a lost Leonardo Da Vinci masterpiece may finally get solved, due to an idea hatched by Ray DuVarney, chair of physics, after a chance meeting of minds.
Italian authorities recently gave the green light to do imaging studies in the Palazzo Vecchio in Florence, to learn if the artist’s legendary mural “The Battle of Anghiari” lies behind it. DuVarney is now an investigator and consultant on a team that is attempting to customize the imaging technology for the Da Vinci project, headed by Maurizio Seracini, director of the Center of Interdisciplinary Science for Art, Architecture and Archaeology at the University of California, San Diego.
“It’s the challenge,” DuVarney says, explaining how he became wrapped up in the quest to unravel one of the great mysteries of Renaissance art. “I’m really intrigued now. I want to see if my idea will work and we can find the painting.”
DuVarney first met Seracini at a physics conference in Taormina, Sicily. An Italian engineer with a passion for art, Seracini told the attendees about his search for “The Battle of Anghiari,” which Da Vinci was commissioned to paint on a wall in Florence’s Hall of Five Hundred. In 1505, Da Vinci began painting a magnificent scene of soldiers on horseback, clashing in battle. He abandoned the project before completion, however, and the mural disappeared when the hall was renovated during the mid-16th century. One of Da Vinci’s admirers, artist and architect Giorgio Vasari, directed the renovation and painted a fresco on the east wall.
Seracini surveyed the hall using radar and discovered that Vasari had built another wall in front of the original east wall, and left a gap between them.
“He told us his hypothesis — that Da Vinci’s mural lies behind the wall where Vasari painted his fresco,” DuVarney says. “Then he challenged all these scientists in the audience to come up with a method to see behind it.”
That evening, while pondering the problem over a glass of Italian red wine, it occurred to DuVarney that nuclear-activated gamma ray spectroscopy might do the trick. The technology is a well-known method of detecting heavy metals, with applications such as determining if mercury is in fish. It can also be used to detect the heavy metals in oil paint. So why not use this technique to take a “picture” through the wall?
Here’s how it would work: Neutrons will pass through a brick wall, but are absorbed by the nuclei of heavy metals. A heavy metal nucleus becomes energized when it absorbs a neutron and then gives off a gamma ray — a beam of high-energy light.
By localizing the movement of neutrons through the wall, the investigators could create a “pixel” and get a reading of the type and intensity of any heavy metals within that area. Since paint often gets its color from heavy-metal compounds, this information could then be used to predict the hue of that pixel. Scanning the wall one large pixel at a time, and repeating the process of analyzing the data, could not only show if a painting adorns the inner wall, but suggest what the painting looks like.
“Maurizio loved the idea,” DuVarney says.
DuVarney recruited an Emory team to help refine the idea, including fellow physicists John Malko, P.V. Rao and Charles Bleau, and Carlos Museum art conservator Renee Stein. Meanwhile, Seracini recruited two private technology companies to work on the project, and the project was recently profiled on “60 Minutes.”
“This is a passion project,” DuVarney says. “It’s more than a physics problem. It’s about finding one of the lost wonders of the world.”